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Effect of pyrogallol on the catecholamine content of the rabbit brain
BiochemicalPharmacology,1%2, Vol. 11,pp. 1109-I110.PergamonPressLtd., Printedin Great Britain.
SHORT COMMUNICATION Effect
of pyrogallol on the catecbolamine (Received
content of tbe rabbit brain
25 June 1962; accepted
20 August
1962)
THERE
have been many reports about the metabolic pathways of catecholamines (CA). Several investigations have indicated that 0-metbylation of CA precedes deamination in uivo, and that monoamine oxidase (MAO) plays only a minor role in the inactivation of infused epinepbrine. Circulating norepinepbrine in the rat is also metabolized predominantly by catechol-O-methyl transferase (COMT).‘? *v a The weak in vitro activity of COMT in rat brain relative to that of MAO, and the fact that the CA content of brain was increased after intraperitoneal injection of iproniazid (a MAO inhibitor), but was not influenced by the intraperitoneal injection of pyrogallol (a COMT inhibitor), suggest that MAO plays a major role in the metabolism of CA in the brain.” We also observed that a significant increase in the CA content of rat brain was produced by the intraperitoneal injection of a new MAO inhibitor, 1037(1-benzyl-2 (4:5-tetrametbylene-3-insoxazolylcarbonyl) hydrazine),6 but that the intraperitoneal injection of pyrogallol failed to increase the CA content of brain. The present experiments were on rabbits (males, weighing about 2 kg), which received intracisternal and intracarotid injections of pyrogallol. The intracarotid injections of pyrogallol (25 mg/kg, twice before killing) produced a slight decrease in the brain CA content from the mean value for saline treated controls (Table 1). A volume, not exceeding 0.2 ml of TABLE 1. EFFECT OF INTRACAROTID INJECTION OF PYROGALLOL ON THE NOREPINEPHRINE CONTENT OF RABBIT BRAIN
Injected material Saline
Pyrogallol
Norepinephrine
content &g/g)
Animal No. Brain stem
Brain cortex
1
0.179
0054
: 4 mean
0.207 0.130 t-PO73 0.147
0.050 0.054 0.093 0063
:
0.125 0.115
0*041 0.045
: mean
0.088 0.103 0.108
0.05 0.0541 0.048
Two injections of pyrogallol (25 mg/kg) into carotid arteries of rabbits were made at 60 min and 30 min before decapitation. Norepinephrine in brain was extracted with 0.4 N percbloric acid and then fractionated with a Duolite C-25 columtGO and estimated by the tribydroxyindole method. pyrogallol dissolved in sterile 0.9 % NaCl solution was injected into the cistema of rabbits. At dosage of 10 mg/kg at 60 min and 30 min before killing, intracistemal injection of pyrogallol caused a marked increase in the brain CA content (Table 2). These results suggest that pyrogallol may not be able to pass through the blood-brain barrier and that COMT also plays a significant role in the metabolism of CA in the brain. 1109
1110
Short communication
Centrally administered pyrogallol resulted in the disappearance of spontaneous activity and marked ataxia. There was diminished muscular tone, so that the rabbits lay on their sides or abdomens and were unable to crouch, sit or walk. Their respiration was very rapid during the first 30 min after the injection. Drowsiness and vomiting were not observed. These effects lasted for about 2 hr. Control rabbits, which received 0.2 ml of sterile 0.9% NaCl solution into the cisterna did not show the above TABLE 2. EFFECTOF INTRACISTERNAL INJECTION OF PYROGALLOL ON THE NOREPINEPHRINE CONTENTOF RABBITBRAIN
Injected material Saline
Norepinephrine
1 2 3 4
i 6 mean Pyrogallol
content (pg/g)
Animal No.
I 2 3 4 :, 7 mean
Brain stem
Brain cortex
0.153 0.148 0.128 0.176 0.129 0.132 0.137
0.090 0.064 0.062 0.062 0.066 0072 0,069
0.585
0.575 0.304 0.280
0.136 0.177 0.082 0.099
0.234 0.206 0,230 0.345
0.142 0.152 0,078 0.124
Two intracisternal injections of pyrogallol (10 mg/kg, volume less than 0.2 ml) were given to rabbits at 60 min and 30 min before decapitation.
symptoms. The behavioural effects of epinephrine, norepinephrine and 5-hydroxytryptamine injected into the cerebral ventricles and the cisterna have been described by several investigators.sy 7y2 It is of great interest to note that the effects of pyrogallol were very similar to those of centrally administered epinephrine and norepinephrine. The present communication suggests that COMT as well as MAO must be taken into consideration in the metabolism of the CA in the brain. More detailed studies are now in progress. Department of Pharmacology, Osaka University Medical School, Osaka, Japan
MATSUOKA MASAMI YOSHIDA HIROSHI IMAIZUMI REIJI
REFERENCES 1. J. 2. J. 3. I. 4. J.
AXELROD, Biochim. biophys. Acta 27, 210 (1958). AXELROD, Physiol. Rev. 39, 751 (1959). J. KOPIN, J. AXELROD and E. GORDON, J. Biol. Chem. 236, (7) 2109 (1961). R. CROUT, C. R. CREVELING and S. UDENFRIEND, J. Pharmacol. Exper. Therap. 132, (2) 269 (1961). 5. K. YAMAMOTO and K. MINESHITA, Folia Pharmacol. Japan (in Japanese), 57, (3) 57 (1961). 6. R. J. SCHAIN, Brit. J. Pharmacol. 17, 261 (1961). 7. W. FELDBERG and S. L. SHERWOOD, J. Physiol. 123, 148 (1954). 8. A. LEIMDORFER and W. R. T. METZNER, Amer.J. Physiol. 157, 116 (1949). 9. J. H. GADDUM and M. VOGT, Brit. J. Pharmacol. 11, 175 (1956). 10. T. NUKADA, M. MATSUOKA and R. IMAIZUMI,Jap.J. Pharmacol. In press.
SHORT COMMUNICATION Effect
of pyrogallol on the catecbolamine (Received
content of tbe rabbit brain
25 June 1962; accepted
20 August
1962)
THERE
have been many reports about the metabolic pathways of catecholamines (CA). Several investigations have indicated that 0-metbylation of CA precedes deamination in uivo, and that monoamine oxidase (MAO) plays only a minor role in the inactivation of infused epinepbrine. Circulating norepinepbrine in the rat is also metabolized predominantly by catechol-O-methyl transferase (COMT).‘? *v a The weak in vitro activity of COMT in rat brain relative to that of MAO, and the fact that the CA content of brain was increased after intraperitoneal injection of iproniazid (a MAO inhibitor), but was not influenced by the intraperitoneal injection of pyrogallol (a COMT inhibitor), suggest that MAO plays a major role in the metabolism of CA in the brain.” We also observed that a significant increase in the CA content of rat brain was produced by the intraperitoneal injection of a new MAO inhibitor, 1037(1-benzyl-2 (4:5-tetrametbylene-3-insoxazolylcarbonyl) hydrazine),6 but that the intraperitoneal injection of pyrogallol failed to increase the CA content of brain. The present experiments were on rabbits (males, weighing about 2 kg), which received intracisternal and intracarotid injections of pyrogallol. The intracarotid injections of pyrogallol (25 mg/kg, twice before killing) produced a slight decrease in the brain CA content from the mean value for saline treated controls (Table 1). A volume, not exceeding 0.2 ml of TABLE 1. EFFECT OF INTRACAROTID INJECTION OF PYROGALLOL ON THE NOREPINEPHRINE CONTENT OF RABBIT BRAIN
Injected material Saline
Pyrogallol
Norepinephrine
content &g/g)
Animal No. Brain stem
Brain cortex
1
0.179
0054
: 4 mean
0.207 0.130 t-PO73 0.147
0.050 0.054 0.093 0063
:
0.125 0.115
0*041 0.045
: mean
0.088 0.103 0.108
0.05 0.0541 0.048
Two injections of pyrogallol (25 mg/kg) into carotid arteries of rabbits were made at 60 min and 30 min before decapitation. Norepinephrine in brain was extracted with 0.4 N percbloric acid and then fractionated with a Duolite C-25 columtGO and estimated by the tribydroxyindole method. pyrogallol dissolved in sterile 0.9 % NaCl solution was injected into the cistema of rabbits. At dosage of 10 mg/kg at 60 min and 30 min before killing, intracistemal injection of pyrogallol caused a marked increase in the brain CA content (Table 2). These results suggest that pyrogallol may not be able to pass through the blood-brain barrier and that COMT also plays a significant role in the metabolism of CA in the brain. 1109
1110
Short communication
Centrally administered pyrogallol resulted in the disappearance of spontaneous activity and marked ataxia. There was diminished muscular tone, so that the rabbits lay on their sides or abdomens and were unable to crouch, sit or walk. Their respiration was very rapid during the first 30 min after the injection. Drowsiness and vomiting were not observed. These effects lasted for about 2 hr. Control rabbits, which received 0.2 ml of sterile 0.9% NaCl solution into the cisterna did not show the above TABLE 2. EFFECTOF INTRACISTERNAL INJECTION OF PYROGALLOL ON THE NOREPINEPHRINE CONTENTOF RABBITBRAIN
Injected material Saline
Norepinephrine
1 2 3 4
i 6 mean Pyrogallol
content (pg/g)
Animal No.
I 2 3 4 :, 7 mean
Brain stem
Brain cortex
0.153 0.148 0.128 0.176 0.129 0.132 0.137
0.090 0.064 0.062 0.062 0.066 0072 0,069
0.585
0.575 0.304 0.280
0.136 0.177 0.082 0.099
0.234 0.206 0,230 0.345
0.142 0.152 0,078 0.124
Two intracisternal injections of pyrogallol (10 mg/kg, volume less than 0.2 ml) were given to rabbits at 60 min and 30 min before decapitation.
symptoms. The behavioural effects of epinephrine, norepinephrine and 5-hydroxytryptamine injected into the cerebral ventricles and the cisterna have been described by several investigators.sy 7y2 It is of great interest to note that the effects of pyrogallol were very similar to those of centrally administered epinephrine and norepinephrine. The present communication suggests that COMT as well as MAO must be taken into consideration in the metabolism of the CA in the brain. More detailed studies are now in progress. Department of Pharmacology, Osaka University Medical School, Osaka, Japan
MATSUOKA MASAMI YOSHIDA HIROSHI IMAIZUMI REIJI
REFERENCES 1. J. 2. J. 3. I. 4. J.
AXELROD, Biochim. biophys. Acta 27, 210 (1958). AXELROD, Physiol. Rev. 39, 751 (1959). J. KOPIN, J. AXELROD and E. GORDON, J. Biol. Chem. 236, (7) 2109 (1961). R. CROUT, C. R. CREVELING and S. UDENFRIEND, J. Pharmacol. Exper. Therap. 132, (2) 269 (1961). 5. K. YAMAMOTO and K. MINESHITA, Folia Pharmacol. Japan (in Japanese), 57, (3) 57 (1961). 6. R. J. SCHAIN, Brit. J. Pharmacol. 17, 261 (1961). 7. W. FELDBERG and S. L. SHERWOOD, J. Physiol. 123, 148 (1954). 8. A. LEIMDORFER and W. R. T. METZNER, Amer.J. Physiol. 157, 116 (1949). 9. J. H. GADDUM and M. VOGT, Brit. J. Pharmacol. 11, 175 (1956). 10. T. NUKADA, M. MATSUOKA and R. IMAIZUMI,Jap.J. Pharmacol. In press.